Gadolinium oxysulfide
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.032.350 |
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| Gd2O2S | |
| Molar mass | 378.5638 g/mol |
| Appearance | white odorless powder |
| Density | 7.32 g/cm3, powder |
| insoluble | |
| Hazards | |
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| Warning | |
| H302, H312, H315, H319, H332, H335 | |
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Related compounds
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Lanthanum oxysulfide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Gadolinium oxysulfide (Gd2O2S), also called gadolinium sulfoxylate, GOS or Gadox, is an inorganic compound, a mixed oxide-sulfide of gadolinium.
Structure
Gadolinium oxysulfide has a trigonal crystal structure (space group 164). Each gadolinium ion is coordinated by four oxygen atoms and three sulfur atoms in a non-inversion symmetric arrangement. The Gd2O2S structure is a sulfur layer with double layers of gadolinium and oxygen in between.[1]
Uses
Ceramic scintillators
The main use of gadolinium oxysulfide is in ceramic scintillators. Scintillators are used in radiation detectors for medical diagnostics. The scintillator is the primary radiation sensor that emits light when struck by high energy photons. Gd2O2S based ceramics exhibit final densities of 99.7% to 99.99% of the theoretical density (7.32 g/cm3) and an average grain size ranging from 5 micrometers to 50 micrometers in dependence with the fabrication procedure.[1] Two powder preparation routes have been successful for synthesizing Gd2O2S: Pr, Ce, F powder complexes for the ceramic scintillators. These preparations routes are called the halide flux method and the sulfite precipitation method. The scintillation properties of Gd2O2S: Pr, Ce, F complexes demonstrate that this scintillator is promising for imaging applications. There are two main disadvantages to this scintillator; one being the hexagonal crystal structure, which emits only optical translucency and low external light collection at the photodiode. The other disadvantage is the high X-ray damage to the sample.[2]
Terbium-activated gadolinium oxysulfide is frequently used as a scintillator for x-ray imaging. It emits wavelengths between 382-622 nm, though the primary emission peak is at 545 nm. It is also used as a green phosphor in projection CRTs, though its drawback is marked lowering of efficiency at higher temperatures.[3] Variants include, for example, using praseodymium instead of terbium (CAS registry number 68609-42-7,[4] EINECS number 271-826-9), or using a mixture of dysprosium and terbium for doping (CAS number 68609-40-5,[5] EINECS number 271-824-8).
Luminescent host material
Gadolinium oxysulfide is a promising luminescent host material, because of its high density (7.32 g/cm3) and high effective atomic number of Gd. These characteristics lead to a high interaction probability for X-ray radiation. Several synthesis routes have been developed for processing Gd2O2S phosphors, including: solid state reaction method, reduction method, combustion synthesis method, emulsion liquid membrane method, and gas sulfuration method. The solid state reaction method and reduction methods are most commonly used because of their high reliability, low cost, and high luminescent properties. (Gd0.99, Pr0.01)2O2S sub-microphosphors synthesized by homogeneous precipitation method are very promising for a new green emitting material to be applied to the high resolution digital X-ray imaging field[6] Gadolinium oxysulfide powder phosphors are intensively used for conversion of X-rays to visible light in medical X-ray imaging. Gd2O2S: Pr based solid state X-ray detectors have been successfully reintroduced to X-ray sampling in medical computed tomography (imaging by sections or sectioning, through the use of any kind of penetrating wave).
Safety
Inhalation may result in lung injuries. Exposure to gadolinium compounds may cause lung and/or liver damage. Contact with the skin may cause rash, redness or dermatitis. When Gadolinium oxysulfide comes in contact with mineral acids, hydrogen sulfide can be produced.[7]
References
- ^ a b Rossner, W., M. Ostertag, and F. Jermann. "Properties and Applications of Gadolinium Oxysulfide Based Ceramic Scintillators." Electrochemical Society Prceeedings, 98, 187-94.
- ^ Greskovich, C.; Duclos, S. (1997). "Ceramic Scintillators". Annual Review of Materials Science. 27: 69–88. Bibcode:1997AnRMS..27...69G. doi:10.1146/annurev.matsci.27.1.69.
- ^ US5115306A, Tsuda, Nobuyuki; Tamatani, Masaaki & Ajiro, Fukaya et al., "Projection crt with a green emitting terbium activated lanthanum oxychloride phosphor exhibiting nearly constant light-output of elevated temperatures", issued 1992-05-19
- ^ "CAS Registry Number 68609-42-7: Gadolinium oxide sulfide (Gd2O2S), praseodymium-doped", Chemical Abstracts Service, American Chemical Society
- ^ "CAS Registry Number 68609-40-5: Gadolinium oxide sulfide (Gd2O2S), dysprosium and terbium-doped", Chemical Abstracts Service, American Chemical Society
- ^ Lian, Jingbao. "Synthesis, Characterization and Photoluminescence Properties of (Gd0.99,Pr0.01)2O2S Sub-microphosphor by Homogeneous Precipitation Method." Optical Materials, 2011-12, 33, 596-600.
- ^ Gadolinium Oxysulfide; MSDS [online]; R.H. Mangels: Hackettstown, NJ, March 15, 1997. http://www.nonius.nl/manualspdf/msdsGadolinumOxysulfide.pdf Archived 2012-04-26 at the Wayback Machine (accessed October 17, 2011)